Ouch's response is perfectly fine from the "physical" point of view... but to me, that's just half of it.
To me the key to a good blow job is the woman's (or man's) desire to do it. A woman can be fantastic at the physical act of a blow job, but if it's methodical and clinical it's never going to be great. The hottest thing about a blow job is the giver diving into it enthusiastically, WANTING to suck that cock.
Totally agree here. And, eager to swallow the load also!